This invention relates generally to video surveillance systems and, more particularly, to determining a position of multiple pan, tilt, and zoom camera assemblies in a spatial grid.
At least some known video surveillance systems include a plurality of video cameras mounted in a housing along with a respective pan, tilt, and zoom (PTZ) assembly. The PTZ permits controlling a movement of the camera to align a viewing area of the camera with an object of interest or location of interest. The zoom portion of the mechanism may be used to adjust a field of view of the camera. The housing typically includes an enclosure and a transparent or semi transparent hemispheric dome. The housing protects the camera from the environment in the location where the camera and PTZ assembly are mounted.
In some applications, the plurality of cameras are coordinated to provide video coverage to a large area with many line-of-sight obstacles. The large area may be, for example, a retail store interior, a warehouse interior, a commercial campus with cameras located internal and external to the buildings of the campus. The obstacles may make following a target of interest traveling through the area difficult. Additionally, manually transferring tracking of the target from one camera to another camera requires determining which camera's field of view the target is moving into at each point of travel through the area. In large systems such determination is cumbersome and may lead to instances wherein the target is lost from view in any camera and is required to be reacquired by at least one of the cameras before tracking the target can continue. Further, obstacles, such as pillars, columns, stacked boxes, racks of clothing, or other retail items, may also make tracking the target difficult.